The CSD procedure involves removal of part of the cervical stellate ganglia and thoracic ganglia of level 2 to 4. These ganglia house the left and right sided nerves that feed the heart and have been implicated in the occurrence of fast abnormal rhythms that cause defibrillator shocks and sudden death. Stimulation of these nerves has been shown to increase the incidence of sudden death and fast abnormal heart rhythms that lead to internal defibrillator shocks called ventricular tachycardia/ventricular fibrillation. Removal of the ganglia of these nerves in animal and human studies has been shown to decrease the incidence of life threatening abnormal rhythms and sudden death.The procedure takes less than 45 minutes on each side and can be performed endoscopically.